8 research outputs found
WEFTA-Laborvergleichsuntersuchungen zur pH-Bestimmung in Fischerei-Erzeugnissen - Eine gemeinsame Aktion der Western European Fish Technologists' Association
12 samples (6 original samples and 6 diluted samples) were analysed by 14 WEFTA laboratories for their pH values in an inter-laboratory comparison exercise. As a result it can be stated that the majority of participating laboratories could determine the pH values very exactly. The pH values obtained are ranging only little around the calculated mean (less than 0.1 pH unit). It could also be demonstrated that the participating institutes could analyse both, pH values in fishery products and aqueous salt solutions. However, also in this exercise a number of outliers and deviating values have been detected. Therefore it is of utmost importance to calibrate the pH electrodes in regular intervals and to maintain them carefully. Intra-laboratory comparison measurements are recommended to detect weak points
TECHNO-ECONOMIC ANALYSIS OF THE OF LAND RECLAMATION PUMPING STATIONS’ ENERGY EFFICIENCY
The energy efficiency of the operation and maintenance of land reclamation pumping stations were conducted at this paper. The study included 12 pump stations located in the southern part of the region of Wielkopolska. All objects are administered by the Great Poland of Land Melioration and Water Units Board in Poznan, District Branch in Leszno. It was found that the work of half of the analyzed pumps is very expensive, and maintenance cost incomparable to the results achieved. Operating costs of the analyzed drainage pumping stations account for 86% of total operating costs, of which 40% is energy cost, and the remaining 14% to the upkeep. Small relative time of operating pumps for leeve and channel pumping stations indicates a for a leap of work, which proves their inefficient use. The use of a larger number of pumps with less power would preserve the continuity and stability of their work
Solvothermal Alcoholysis Routes for Recycling Polylactide Waste as Lactic Acid Esters
In
this work, we investigated the possible use of polylactide (PLA),
a biodegradable polymer obtained from renewable biofeedstock, to produce
a range of industrially useful lactic acid esters. We describe a simple
and convenient solvothermal alcoholysis method for large-scale recycling
of PLA resins or residues from disposable packaging in the presence
of the appropriate alcohol under catalyst-free or catalytic conditions.
This process proceeds easily both without and with a catalyst. The
results show that the best catalytic activities involve magnesium
and calcium alkoxides synthesized in situ from organometallic or metallic
precursors and an alcohol. We determined the crystal structure of
the chiral mononuclear postcatalyst [Ca(LAc)<sub>2</sub>(EL)<sub>2</sub>] (<b>1</b>; LAc = lactic acid anion, EL = ethyl lactate),
obtained directly from the reactor. Particular emphasis is placed
on the operating conditions and high activity of the catalyst used.
Key factors that affect the catalytic activity and reaction mechanism
are also highlighted
Synthesis and Structural Characterization of Magnesium Drug Complexes: Efficient Initiators for Forming Polylactide–Drug Conjugates
Five novel magnesium alkoxides supported
by drug chelating agents <i>pridinolum</i> (PriOH = 1,1-diphenyl-3-(1-piperidinyl)-1-propanol)
and <i>venlafaxinum</i> (VenlOH = (<i>RS</i>)-1-[2-dimethylamino-1-(4-methoxyphenyl)-ethyl]cyclohexanol)
were successfully synthesized and characterized. Direct reaction of
PriOH and VenlOH with MgBu<sub>2</sub> (1:1) in toluene gives the
dimeric compounds [Mg(μ,η<sup>2</sup>-OPri)<sup><i>n</i></sup>Bu]<sub>2</sub> (<b>1</b>) and [Mg(μ,η<sup>2</sup>-VenlO)<sup><i>n</i></sup>Bu]<sub>2</sub> (<b>2</b>), respectively. Furthermore, the crystallization of an equimolar
mixture of <b>1</b> and <b>2</b> in toluene yields heteroleptic
magnesium complex [Mg(μ,η<sup>2</sup>-OVenl)(η<sup>1</sup>-OPri)]<sub>2</sub> (<b>3</b>). Moreover, reactions
of <b>1</b> and <b>2</b> with 2 molar equivs of the corresponding
drug–ligands give the homoleptic magnesium bis-alkoxides [Mg(μ,η<sup>2</sup>-OPri)(η<sup>1</sup>-OPri)]<sub>2</sub> (<b>4</b>) and [Mg(μ,η<sup>2</sup>-OVenl)(η<sup>1</sup>-OVenl)]<sub>2</sub> (<b>5</b>). The treatment of compound <b>1</b> with 2 equivs of VenlOH or <b>2</b> with 2 equivs of PriOH
leads to the formation of <b>3</b>. Complexes <b>1</b>–<b>5</b> were characterized by elemental analysis,
nuclear magnetic resonance, and single crystal X-ray diffraction (for <b>1</b>–<b>4</b>). It was found that complexes <b>1</b>–<b>5</b> are efficient initiators of the ring-opening
polymerization of l-LA, yielding PLA-OPri and PLA-OVenl conjugates,
respectively. Moreover, the ring-opening polymerization of l-LA initiated by <b>3</b> led to the simultaneous generation
of a blend of poly-l-lactide conjugates with end-capped VenlO
and PriO groups
Molecular Routes to Group IV Magnesium and Calcium Nanocrystalline Ceramics
The effect of alkaline-earth-metal
alkoxides on the protonolysis of Cp<sub>2</sub>M′Cl<sub>2</sub> (M′ = Ti, Zr, Hf; Cp = cyclopentadiene) was investigated.
This approach enabled the design of compounds with well-defined molecular
structures to generate high-purity binary metal oxides. Single-source
molecular precursors with structures of [M<sub>2</sub>M′<sub>2</sub>(μ<sub>3</sub>-OEt)<sub>2</sub>(μ-OEt)<sub>4</sub>(OEt)<sub>6</sub>(EtOH)<sub>4</sub>] with M = Mg and M′ =
Ti (<b>1</b>), Zr (<b>2</b>), and Hf (<b>3</b>),
[Ca<sub>6</sub>Ti<sub>4</sub>(μ<sub>6</sub>-O)<sub>2</sub>(μ<sub>4</sub>-O)<sub>2</sub>(μ<sub>3</sub>-OEt)<sub>12</sub>(OEt)<sub>12</sub>(EtOH)<sub>6</sub>Cl<sub>4</sub>] (<b>4</b>), and [M<sub>2</sub>M′<sub>2</sub>(μ<sub>4</sub>-O)(μ-OEt)<sub>5</sub>(OEt)<sub>4</sub>(EtOH)<sub>4</sub>Cl]<sub><i>n</i></sub> with M = Ca and M′ = Zr (<b>5</b>) and Hf (<b>6</b>) were prepared via elimination of the cyclopentadienyl ring
from Cp<sub>2</sub>M′Cl<sub>2</sub> as CpH in the presence
of M(OEt)<sub>2</sub> and ethanol (EtOH) as a source of protons. Meanwhile,
similar reactions involving the initial substitution of Cl ligands
by OEt groups in Cp<sub>2</sub>M′Cl<sub>2</sub> (M′
= Ti, Zr, Hf) resulted in the formation of [M<sub>2</sub>M′<sub>2</sub>(μ<sub>3</sub>-OEt)<sub>2</sub>(μ-OEt)<sub>4</sub>(OEt)<sub>6</sub>(EtOH)<sub>4</sub>] with M = Ca and M′ =
Ti (<b>7</b>), Zr (<b>8</b>), and Hf (<b>9</b>).
The precursors were characterized by elemental analysis, NMR spectroscopy,
and single-crystal X-ray structural analysis. Magnesium compounds <b>1</b>–<b>3</b> decomposed at 750–850 °C
to give MgTiO<sub>3</sub> along with small amounts of Mg<sub>2</sub>TiO<sub>4</sub>, Mg<sub>2</sub>Zr<sub>5</sub>O<sub>12</sub>, or Mg<sub>2</sub>Hf<sub>5</sub>O<sub>12</sub> binary metal oxides. The thermolysis
of calcium compounds <b>4</b> and <b>7</b>–<b>9</b> led to highly pure CaTiO<sub>3</sub>, CaZrO<sub>3</sub>,
or CaHfO<sub>3</sub> perovskite-like oxide particles with diameters
of 20–30 nm